Alarm device



April 27 1926.

1,582,745 H. H. GEFFCKEN El AL ALARM DEVICE Filed Oct. 22, 1924 -JUUUL WW 7 INVENTORS fiuao/f Hermann his ATTORNEYS atgented Apr 27, 192%,

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LEIPZIC-GOHLIS, GEBEALN'EZ 1 ALKRM Davina.

Application filed October 221'19M. Serial li'o. 745,118.

Z'oaZZ whom it may concern:

l Be it known that we, Rnnonr HERMANN Hnmnrcn Gnrrcxnn and RUooLr HANS RICHTER, citizens of Germany, and residing at Leipzic-Gohlis, Germany, have invented certain new and useful improvements in or Relating to Alarm Devices (for which we have filed application in Germany August 23, 1923, Serial No. 669,755), of which the 110 following is a specification.

This invention relates to alarm devices, and is directed more particularly to anarrangement which is especially well adapted for useas a burglar and fire alarm.

33 The object of this invention is to provide an alarm device which is highly dependable and which is not susceptible to extraneous influences tending to cause false operatio thereof. v

has extremely sensitive electromagnetic devices, such as relays in conjunction with burglar and fire alarms and experience has indicated that those devices are very likely to be influenced by extraneous disturbances,

' as for example, heavy vibrations, which are apt to arise from various causes. This sometimes results in the giving of false alarms.

The prevention of such false alarm is the so thing with which the present invention is concerned. Y

In accordance with this invention electrical discharge tubes are employed instead of the highly sensitive electromagnetic devices heretofore used. The electrical discharge tubes referred to (a common formwhich is the well-known luminous glow-lamp) are characterized in that they do not function at all until a certain minimum voltage has been applio d to their electrodes. This characteristic is taken advantage of in the present invention to produce a ighly sensitive arrangement which at the same time is not likely to be effected by "any amount of vibratory influence to whlch the device is not intended to respond.

In the c1rcu1t arrangement shown in the accom anying drawing, 1 indicates an eledtrical ischarge device of the g'low-lamp-type comprisin electrodes 2 and 3 which are contained wit in gas-filled chamber enclosed by the glass envelope 4. 5 and 6 indicate direct current sup ly conductors to which the terminals of t e discharge device 1 are conrent. If it is assumed that the current sup- Heretofore it has been the practice. to uti- .ly flowing through the shunt path compris-v mg the conductor 9 and resistance 10.

also apparent that the volta e across the ter- T device,'and withthis increase in voltage, t e

nec ted. A resistance 7 is shown inserted in the conductor 6 in series with the;discharge device and a suitable electrically operative alarm or signal releasing device 8 is shown inserted in the conductor 5 also in series with I the discharge dev ce.

The discharge device is shunted by the conductor 9 having in series, with it a. resistance. element 10. Conductor 6 is shown grounded at 11. The values of resistances 7 and 1.0 and the voltage impressed on the 35 conductors 5' and 6 are so chosen that normally the voltage across the terminals of the discharge device 1 is just below the point at which the latter will function to pass ourp ly to conductors 5 and 6 is 250 volts and that the discharge device 1 will function at 160 volts, the resistance 7 and 10 may be so chosen that the voltage normally impressed across the terminals of the discharge device is about 159 volts, that is, just below the value at which the discharge vdevice will func' tion. Under these conditions it has been Y found in one instance that the resistance '7 may be about 5000 ohms and the resistance 10 about 13000 ohms. From a consideration of the diagram it is apparent that a small current is continualt is 86 minals of the discharge dance is lowered by reason of the series resistance 7. By opening the shunt circuit, as for exam le, by cutting the conductor 9 or by shunting or par- 0 tially shunting the-resistance 7, the voltage impressed across the terminals'of the (11S- charge device may be increased to a point above that necessary for it to function. With the circuit grounded as indicated a ground'connection to the shunt path, even through a high resistance such as that of a human body, would'cause an increase in the voltage across the'terminals of the dischar e 10 0 discharge device functions, whereupon its resistance immediately drops and suflicient currentis passed to operate the alarm. Once started the discharge device will continue to operate'on a voltage considerably lower than the starting voltage.

Alarm 8 is, of course, so designed that it will not operate onthe small current flowing 1 so arranged that it will either-be touched or broken by an intruder. ()bviously, if it is intended that mere contact with the, conductor 9 will cause the alarm to operate, provision must be made so that the body of the person touching the conductor will, at the same time, be grounded, thereby forming a high resistance shunt across the resistance element 7 and consequently increasing the voltage applied to the discharge device to a value sufiicient to cause it to function.

- The embodimentof the invention. illusdischarge potential, said system also including ana arm means set into operation on the passage of current through the discharge tube.

' 2. In a'protect-ive alai'm system, a circuit' extending through an area to be protected,

means for supplying current at a substanti ally constant potential to said circuit, a dischargeitube shunting said circuit between trated and herein described has purposely wthe source of current and said protected area,

been made very simple so that the principles of the invention may be readily understood. It is thoughtthat many specific applicationsof the invention will readily suggest themselves to those skilled in the art.

1 If alternatingcurrent is to be utilized instead of direct current, it is sometimes preferable so to form the discharge device that the predetermined minimum voltage at which it functions or the current strength of the discharge from the two directions of current are different, so that a rectifying action occurs. In this way it is possible to actuate a direct current relay for releasing the signal. Furthermore, when employing alternating currentdischarge-devices, a direct current voltage may be usefully superposed on the alternatin current voltage in order to maintain a dlscharge when once set up.

The invention des ribed herein, but only in accordance with the scope of the appended claims. By the term alarm as used in the claims,

' equivalent elements such as signals and signal releasingjdevices and relays are ineluded.

" What is claimed is 1. In a protective alarm system, a circuit! should, thereiore, not be construed as limited to the arrangement I.

the potential of the source being above the tube discharge potential and the resistance of the circuit being such that the potential across the tube is normally maintained below such dischargepotential, said system through the area to be protected, the potential of the source being above the tub'e discharge potential, a resistance between the source of current and the tube, a resistance in the circuit extending through the area to be protected, the-valuesof the resistances being such that the potential normally impressed acrossthe discharge tube is slightly below that necessary to cause the occurrence j of a discharge therein,'said system also in- \cluding an alarm meansset into operation on the passage of current through the discharge tube.

In testimony whereof we afiix our sig-v natures.

RUDOLF stamina HEINRICH crrrcxrn. RUDOLF mus RICHTER. 

